Update header files to not specify "using namespace std"

Header files should not specify "using namespace std"; it pollutes the namespace.
Prototypes should use std::type format instead.
Problems in our code:

$ find src oel_* viirs_lib -type f -name "*.h*" -exec grep -THl "using namespace std" {} \;|sort
oel_hdf4/libhdf5utils/hdf5utils.h
oel_util/libnetcdfutils/cdl_utils.h
src/afrt/AfrtProcess.h
src/dtdb/darktarget/DtAlgorithm.h
src/dtdb/darktarget/DtLutNetcdf.h
src/dtdb/DDAlgorithm.h
src/dtdb/DDAncillary.h
src/dtdb/DDataset.hpp
src/dtdb/DDProcess.h
src/dtdb/DDSensor.h
src/dtdb/deepblue/DbAlgorithm.h
src/dtdb/deepblue/DbLutNetcdf.h
src/dtdb/resam_viirs/RsViirs.h
src/dtdb/resam_viirs/RsViirs.hpp
src/l1agen_hawkeye/hawkeyeUtil.h
src/l1agen_hawkeye/l1agen_hawkeye.h
src/libcloud/dim_mgr.hpp
src/tmatrix/TmProcess.h
viirs_lib/libViirsCal/VcstCalNetcdfInputItem.h
viirs_lib/libViirsCal/VcstObc.h
viirs_lib/libViirsCmn/VcstCmnGeo.h
viirs_lib/libViirsCmn/VcstCmnLutInputItem.h
viirs_lib/libViirsGeo/ObpgReadGrid.h
viirs_lib/libViirsGeo/VcstGeoNetcdfInputItem.h